Ever since I put a plane into a tree (and the wing was severed in two, fuselage cracked in a half dozen places), I've been thinking of rebuilding it from scratch. It's a mini ultra stick, if that helps, and I was wondering what a good amount of main wing/horizontal stab incidence would be. Would two degrees up on the wing and two degrees down on the stab be sufficient?

That would climb like mad. If its fully symmetrical airfoil, 0 -0-0 works fine. If its semi symmetrical, 0 to +1 on wing, same on stab, and a degree or two of down thrust. If flat bottom wing, 0 on wing, 1-2+ on stab, 1-3 down thrust. General numbers, perfecting takes time.

Well, I'm debating wether or not to keep the straight wing with constant chord, or go with a bit of a taper for a little more speed. I'll be using a fully symmetrical airfoil regardless. Inverted performance must match upright performance.

But if you say zero wing incidence and zero empennage incidence would work for sport flying, I'll make sure that gets into the build.

The pattern guys will wind up somewhere around 1/2+ on the wing about 1ish down thrust and maybe a tad positive on the stab. Now they do have adjustable incidence on the wing and stab which makes that very much easier to change.

Modern pattern birds move slower than days of old too. I've found that fully symmetrical wings fly well and trim well with 0-0-0 as a starting point.
As an aside, tapering won't add nearly as much speed as cutting span and using efficient wing tips.